Tumor-infiltrating platelets promote the growth of lung adenocarcinoma.

Purpose: Platelets could promote tumor growth and metastasis. However, the role of platelets in different subtypes of non-small cell lung cancer (NSCLC) and platelet infiltration in local tumor tissue remain unclear.

Methods: Initially, platelet infiltration in lung adenocarcinoma (ADC) and lung squamous cell carcinoma (SCC) was estimated by CD41 expression using immunohistochemistry. Subsequently, co-incubation of NSCLC cell lines and platelets was performed to compare the ability of binding platelets. Subcutaneous tumor models were established to assess the ability of platelets to promote tumor growth. Then, RNA-seq data of NSCLC was used to identify differentially expressed genes and enriched pathways. Lastly, a clinical cohort comprising of ADC and SCC patients as well as meta-analysis was analyzed to compare the difference of coagulation associated clinical parameters.

Results: We found high platelet infiltration in ADC, especially of advanced disease and metastases, whereas few platelets were observed in SCC. Moreover, ADC cell lines exhibited strong ability of binding platelets compared with SCC cell lines. Platelets could also promote the growth of ADC cell lines in vivo. Furthermore, coagulation cascades and fibrinogen were upregulated in ADC. And chemical inhibition of GPIIb/IIIa-fibrinogen axis reduced the binding of ADC cells and platelets. ADC patients were also in a hypercoagulable state characterized by higher d-dimer level and shorter clotting time. Finally, meta-analysis identified a higher risk of venous thromboembolism (VTE) in ADC patients and low molecular weight heparin (LMWH) treatment was effective at reducing this risk.

Conclusions: This study identified the differences of platelet infiltration and coagulation between ADC and SCC patients, which may inform the development of anticoagulation therapies for NSCLC.